Personal knowledge management

Hosted workspace combining block-based documents, relational databases, wikis and project views, with an API and built-in AI features

Local-first Markdown note-taking app with bidirectional links, graph view and a large community plugin ecosystem; optional paid Sync and Publish

Open-source, outliner-based knowledge base storing notes as local Markdown or Org-mode files with block references, queries and a graph view

Apple's built-in notes app for Mac, iPhone, iPad and iCloud.com with folders, tags, attachments, handwriting, shared notes and on-device search

Block-based document and notes app with native Apple, Windows and web clients, structured pages, collections and shareable published documents

Markdown note-taking app for Mac, iPhone and iPad from Shiny Frog with nested tags, note links and iCloud sync, free with a Pro subscription